Metallic material for a connecting part and a method of producing the same

ABSTRACT

A metallic material for a connecting part, having a rectangular wire material of copper or a copper alloy as a base material, and formed at an outermost surface thereof, a copper-tin alloy layer substantially composed of copper and tin, wherein the copper-tin alloy layer of the outermost surface further contains at least one selected from the group consisting of zinc, indium, antimony, gallium, lead, bismuth, cadmium, magnesium, silver, gold, and aluminum, in a total amount of 0.01% or more and 1% or less in terms of mass ratio with respect to the content of the tin.

TECHNICAL FIELD

The present invention relates to a metallic material for a connectingpart and a method for producing the same, and more particularly, thepresent invention relates to a metallic material for a connecting parthaving sufficient gloss after a reflow, and a method for producing thesame.

BACKGROUND ART

A plated material produced by providing a plating layer of, for example,tin (Sn) or a tin alloy, on an electroconductive base material, such ascopper (Cu) or a copper alloy (hereinafter, appropriately referred to asbase material), is known as a high performance conductor material havingthe excellent electroconductivity and mechanical strength of the basematerial, as well as the excellent electrical connectivity, corrosionresistance, and solderability of the plating layer. Thus, such platedmaterials are widely used in various terminals, connectors, and thelike.

In recent years, since a fitting-type connector is multipolarized withadvancement of electronic control, a considerable force is necessary forplugging a group of male terminals into/out of a group of femaleterminals. In particular, plugging-in/out such a connector is difficultin a narrow space such as the engine room of a vehicle, and it has beenstrongly demanded to reduce the force for plugging in/out such aconnector.

In order to reduce the plugging-in/out force, the Sn plating layer onthe surface of the connector terminal may be thinned to weaken contactpressure between the terminals. However, because the Sn plating layer issoft, a fretting phenomenon may occur between contact faces of theterminals, thereby causing inferior conduction between the terminals.

In the fretting phenomenon, the soft Sn plating layer on the surface ofthe terminal wears and is oxidized, becoming abrasion powder havinglarge specific resistance, due to fine vibration between the contactfaces of the terminals caused by vibration and changes in temperature.When this phenomenon occurs between the terminals, conduction betweenthe terminals results in inferior. The lower the contact pressurebetween the terminals, the more the fretting phenomenon is apt to occur.

Patent Literature 1 describes an electrically conductive material for aconnecting part, having a Cu—Sn alloy coating layer and a Sn coatinglayer, formed in this order, on the surface of a base material formedfrom a Cu strip, wherein the Cu—Sn alloy coating layer has the exposurearea ratio at the material surface of 3 to 75%, the average thickness of0.1 to 3.0 μm, and the Cu content of 20 to 70 at %; and the Sn or Snalloy coating layer has the average thickness of 0.2 to 5.0 μm. It isalso described that a Cu—Sn alloy coating layer is formed by performinga reflow treatment.

According to Patent Literature 1, when this electrically conductivematerial is used in, for example, a multipole connector in automobiles,a low insertion force upon fitting of male and female terminals isattained, and the assembly operation can be efficiently carried out; andthe electrically conductive material is considered to be able tomaintain electrical reliability (low contact resistance), even ifmaintained for a long period of time under a high temperatureatmosphere, or even under a corrosive environment.

-   Patent Literature 1: JP-A-2006-77307 (“JP-A” means unexamined    published Japanese patent application)

DISCLOSURE OF INVENTION Technical Problem

However, although the electrically conductive material for a connectingpart described above has a base material formed from a Cu strip, whenthe base material is a rectangular wire material, the surface propertiesafter heat treatment can be deteriorated at the time of the productionof a Cu—Sn alloy plated wire or the production of a Sn plated wire, by aheat treatment such as a reflow treatment. Furthermore, there is alsoobserved a phenomenon in which whiskers that may cause an electric shortcircuit accident are generated even though the material has beensubjected to a reflow treatment. Such phenomena are thought to be causedbecause, for example, Sn present on the rectangular wire material meltsand flows during the reflow treatment and the distribution of Sn becomesnon-uniform. However, the Patent Literature 1 does not have anydescriptions at all on the case where the base material is a rectangularwire material, and in order to solve this problem, a new approach willbe needed.

Thus, it is an object of the present invention to provide a metallicmaterial for a connecting part which has good surface properties after aheat treatment and has good solderability in subsequent processes, andto provide a method for producing the metallic material.

It is another object of the present invention to provide a metallicmaterial for a connecting part which material has good surfaceproperties after a heat treatment and hardly causes whiskers, and amethod for producing the metallic material.

Solution to Problem

According to the present invention, there is provided the followingmeans:

-   (1) A metallic material for a connecting part, having a rectangular    wire material of copper or a copper alloy as a base material, and    formed at an outermost surface thereof, a copper-tin alloy layer    substantially composed of copper and tin, wherein the copper-tin    alloy layer of the outermost surface further contains at least one    selected from the group consisting of zinc, indium, antimony,    gallium, lead, bismuth, cadmium, magnesium, silver, gold and    aluminum, in a total amount of 0.01% or more and 1% or less in terms    of mass ratio with respect to the content of the tin;-   (2) A metallic material for a connecting part, having a rectangular    wire material of copper or a copper alloy as a base material, and    formed at an outermost surface thereof, an alloy layer containing    tin as a main component, wherein the alloy layer containing tin as a    main component at the outermost surface contains an element selected    from at least one group among the following two groups of (A) and    (B), in a total amount of 0.01% by mass or more and 2% by mass or    less:

(A) at least one element selected from the group consisting of gallium,indium, lead, bismuth, cadmium, magnesium, zinc, sliver, and gold iscontained, in an amount of 0.01% by mass or more and 1% by mass or lessfor individual element, and

(B) at least one element selected from the group consisting of aluminumand copper is contained, in an amount of 0.01 to 0.5% by mass forindividual element;

-   (3) The metallic material for a connecting part as described in the    above item (1) or (2), wherein a layer of nickel, cobalt, iron, or    an alloy thereof is formed on the base material;-   (4) A method for producing a metallic material for a connecting    part, the method including: providing a rectangular wire material of    copper or a copper alloy as a base material, forming on this base    material a tin alloy plating layer containing at least one selected    from the group consisting of zinc, indium, antimony, gallium, lead,    bismuth, cadmium, magnesium, silver, gold, copper and aluminum, in a    total amount of 0.01% by mass or more and 1% by mass or less, to    thereby obtain an intermediate material; subsequently subjecting the    intermediate material to a heat treatment, and thereby forming an    alloy layer containing copper and tin at the outermost surface;-   (5) The method for producing a metallic material for a connecting    part as described in the above item (4), wherein the thickness of    the tin alloy plating layer prior to the heat treatment is 0.3 to    0.8 μm;

(6) The method for producing a metallic material for a connecting partas described in the above item (4), wherein a layer of nickel, cobalt,iron, or an alloy thereof, and a copper plating layer or a copper alloyplating layer are provided, in order from the side closer to the basematerial, between the base material and the tin alloy plating layer, andthereby the intermediate material is obtained;

(7) The method for producing a metallic material for a connecting partas described in the above item (6), wherein the thickness of the tinplating layer or the tin alloy plating layer prior to subjecting to theheat treatment is 0.3 to 0.8 μm, and the ratio (Sn thickness/Cuthickness) of the thickness of the tin plating or tin alloy platinglayer (Sn thickness) to the thickness of the copper plating layer (Cuthickness) is less than 2;

(8) A method for producing a metallic material for a connecting part,the method including: providing a rectangular wire material of copper ora copper alloy as a base material, forming on this base material a tinalloy plating layer containing an element selected from at least onegroup among the following two groups (A) and (B), in a total amount of0.01% by mass or more and 2% by mass or less, to thereby obtain anintermediate material; and then subjecting the intermediate material toa heat treatment:

(A) at least one element selected from the group consisting of gallium,indium, lead, bismuth, cadmium, magnesium, zinc, sliver, and gold iscontained, in an amount of 0.01% by mass or more and 1% by mass or lessfor individual element, and

(B) at least one element selected from the group consisting of aluminumand copper is contained, in an amount of 0.01 to 0.5% by mass forindividual element;

-   (9) The method for producing a metallic material for a connecting    part as described in the above item (8), wherein the thickness of    the tin alloy plating layer prior to the heat treatment is 0.8 to    1.2 μm;-   (10) The method for producing a metallic material for a connecting    part as described in the above item (8), wherein a layer of nickel,    cobalt, iron or an alloy thereof, and a copper plating layer or a    copper alloy plating layer are provided, in order from the side    closer to the base material, between the base material and the tin    alloy plating layer, and thereby the intermediate material is    obtained;-   (11) The method for producing a metallic material for a connecting    part as described in the above item (10), wherein the thickness of    the tin plating layer or the tin alloy plating layer prior to    subjecting to the heat treatment is 0.8 to 1.2 μm, and the ratio (Sn    thickness/Cu thickness) of the thickness of the tin plating or tin    alloy plating layer (Sn thickness) to the thickness of the copper    plating layer (Cu thickness) is 2 or more; and-   (12) The method for producing a metallic material for a connecting    part as described in any one of items (4) to (11), wherein the heat    treatment is a reflow treatment.

Hereinafter, a first embodiment of the present invention means toinclude the material for a connecting part, as described in the items(1) and (3) {limited to those dependent on the item (1)}, and the methodfor producing a metallic material for a connecting part, as described inthe items (4) to (7), and (12) {limited to those directly or indirectlydependent on the item (4)}.

A second embodiment of the present invention means to include themetallic material for a connecting part, as described in (2) and (3){limited to the one dependent on the item (2)} and the method forproducing a metallic material for a connecting part, as described in (8)to (11), and (12) {limited to the one directly or indirectly dependenton the item (8)}.

Herein, the present invention means to include all of the above firstand second embodiments, unless otherwise specified.

ADVANTAGEOUS EFFECTS OF INVENTION

The metallic material for a connecting part of the present invention,which has, at the outermost surface of a rectangular wire material(including a rectangular rod material) of copper and a copper alloy as abase material, a layer substantially composed of copper and tin andcontaining at least one selected from the group consisting of zinc,indium, antimony, gallium, lead, bismuth, cadmium, magnesium, silver,gold, and aluminum, in a total amount of 0.01% or more and 1% or less interms of mass ratio with respect to the content of tin, can serve as ametallic material that is independent of surface unevenness of the basematerial surface, has sufficient gloss after a heat treatment, and hasvery high preliminary solderability and post-plating property for thepromotion of wetting by solder.

The metallic material for a connecting part of the present invention,which has, at the outermost surface of a rectangular wire material(including a rectangular rod material) of copper or a copper alloy as abase material, a layer containing tin as a main component and furthercontaining an element selected from at least one group among thefollowing two groups of (A) and (B) in a total amount of 0.01% by massor more and 2% by mass or less, can serve as a metallic material that isindependent of surface unevenness of the base material surface, hassufficient gloss after a heat treatment, and does not easily have theoccurrence of whiskers;

(A) at least one element selected from the group consisting of gallium,indium, lead, bismuth, cadmium, magnesium, zinc, sliver, and gold iscontained, in an amount of 0.01% by mass or more and 1% by mass or lessfor individual element;

(B) at least one element selected from the group consisting of aluminumand copper is contained, in an amount of 0.01 to 0.5% by mass forindividual element.

Other and further features and advantages of the invention will appearmore fully from the following description, appropriately referring tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially enlarged schematic cross-sectional view of ametallic material for a connecting part (rectangular wire material) ofExample 1.

FIG. 2 is a partially enlarged schematic cross-sectional view of ametallic material for a connecting part (rectangular wire material) ofExample 2.

FIG. 3 is a partially enlarged schematic cross-sectional view of ametallic material for a connecting part (rectangular wire material) ofExample 3.

FIG. 4 is a partially enlarged schematic cross-sectional view of ametallic material for a connecting part (rectangular wire material) ofExample 4.

FIG. 5 is a partially enlarged schematic cross-sectional view of ametallic material for a connecting part (rectangular wire material) ofExample 5.

FIG. 6 is a partially enlarged schematic cross-sectional view of ametallic material for a connecting part (rectangular wire material) ofExample 6.

FIG. 7 is a partially enlarged schematic cross-sectional view of ametallic material for a connecting part (rectangular wire material) ofExample 7.

-   1 Base material-   2 Copper-tin alloy layer-   3 Nickel layer-   11 Base material-   12 Tin alloy layer-   13 Copper-tin alloy layer-   14 Nickel layer

BEST MODE FOR CARRYING OUT THE INVENTION

The metallic material for a connecting part according to a preferredembodiment (the “first embodiment) of the present invention has arectangular wire material formed of copper or a copper alloy as a basematerial, and has, at the outermost surface thereof, a layersubstantially composed of copper and tin and further containing at leastone selected from the group consisting of zinc (Zn), indium (In),antimony (Sb), gallium (Ga), lead (Pb), bismuth (Bi), cadmium (Cd),magnesium (Mg), silver (Ag), gold (Au), and aluminum (Al), in a totalamount of 0.01% or more and 1% or less in terms of mass ratio withrespect to the content of tin.

The metallic material for a connecting part of another preferredembodiment (the “second embodiment”) of the present invention has arectangular wire material formed of copper or a copper alloy as a basematerial, and has, at the outermost surface thereof, a layer containingtin as a main component and further containing an element selected fromat least one group among the following two groups of (A) and (B), in atotal amount of 0.01% by mass or more and 2% by mass or less;

(A) at least one element selected from the group consisting of Ga, In,Pb, Bi, Cd, Mg, Zn, Ag, and Au is contained, in an amount of 0.01% bymass or more and 1% by mass or less for individual element;

(B) at least one element selected from the group consisting of Al and Cuis contained in an amount of 0.01 to 0.5% by mass for individualelement.

As the base material for the metallic material for a connecting part, ofthe present invention, copper or a copper alloy is used, and use may bepreferably made of copper and copper alloys, such as phosphor bronze,brass, nickel silver, beryllium copper, and Corson alloy, each of whichhas the electroconductivity, mechanical strength, and heat resistancerequired in connectors.

The shape of the base material is preferably a rectangular wire material(including a rectangular rod material). For the rectangular wirematerial, the cross-sectional shape may be any of square, rectangle, andregular hexagon, or may be an irregularly shaped wire. A rectangularwire material having an approximately square cross-sectional shape canbe used with preference in the present invention.

According to the present invention, it is preferable to provide a Cuplating layer by performing Cu underlying plating on the rectangularwire material. However, in the case of adopting a constitution capableof forming a layer of a copper-tin alloy below the tin alloy plating ofthe outermost layer by a heat treatment that will be described later,the metallic material may not have a underlying. When a Cu plating layeris provided, the formation of an alloy layer containing Cu and Sn can beeasily achieved. The thickness of the Cu plating layer is preferably0.01 to 3.0 μm, and more preferably 0.05 to 1.0 μm.

Further, in order to enhance heat resistance, a nickel plating layer maybe formed, by providing a nickel (Ni) underlying plating having abarrier property that prevents the diffusion of metal from the lowerlayer, between the base material and the copper underlying. The nickelunderlying plating may be a Ni alloy plating, such as a Ni—P-based, aNi—Sn-based, a Co—P-based, a Ni—Co-based, a Ni—Co—P-based, aNi—Cu-based, a Ni—Cr-based, a Ni—Zn-based, or a Ni—Fe-based. Ni and Nialloys are not deteriorated in the barrier function even in a hightemperature environment. Furthermore, in addition to nickel, sincecobalt (Co), iron (Fe) or an alloy thereof also exhibits the sameeffects, these metals are suitably used as the underlying layer.

When the thickness of the layer formed from nickel, cobalt, iron, or analloy thereof is less than 0.02 μm, the barrier function is notsufficiently exhibited. When the thickness is greater than 3.0 μm, theplating strain increases, and the plating is apt to be peeled off fromthe base material. Therefore, the thickness is preferably 0.02 to 3.0μm. The upper limit of the thickness of the layer formed from nickel,cobalt, iron, or an alloy thereof is preferably 1.5 μm, and morepreferably 1.0 μm, taking the terminal processability intoconsideration.

In the present invention, the surface layer of the material is providedwith a tin alloy plating. In the metallic material for a connecting partof the first embodiment, this tin alloy plating contains at least oneselected from the group consisting of zinc, indium, antimony, gallium,lead, bismuth, cadmium, magnesium, silver, gold, copper, and aluminum,in a total amount of 0.01% by mass or more and 1% by mass or less.Furthermore, in the metallic material for a connecting part of thesecond embodiment, this tin alloy plating contains an element selectedfrom at least one group among the following two groups of (A) and (B),in a total amount of 0.01% by mass or more and 2% by mass or less;

(A) at least one element selected from the group consisting of Ga, In,Pb, Bi, Cd, Mg, Zn, Ag, and Au is contained, in an amount of 0.01% bymass or more and 1% by mass or less for individual element;

(B) at least one element selected from the group consisting of Al and Cuis contained, in an amount of 0.01 to 0.5% by mass for individualelement.

In the metallic material for a connecting part of the first embodiment,if the thickness of the tin alloy plating is too small, the environmentresistance or the like of the copper-tin alloy layer that is finallyformed at the outermost surface is hardly exhibited, and therefore, thethickness is preferably 0.3 μm or more. If the thickness of the tinalloy plating is too large, the tin alloy eventually remains on thesurface of the copper-tin alloy layer and causes the frettingphenomenon, and therefore, the thickness is more preferably 0.3 to 0.8μm, and even more preferably 0.3 to 0.6 μm.

In the metallic material for a connecting part of the second embodiment,if the thickness of the tin alloy plating is too small, the heatresistance and environment resistance of tin are hardly exhibited, andtherefore, the thickness is preferably 0.3 μm or more, more preferably0.8 to 1.2 μm, and even more preferably 0.8 to 1.0 μm.

In the present invention, the tin alloy plating may be formed byperforming electroless plating, but it is preferable to form the tinalloy plating by performing electroplating.

The Sn electroplating of the surface layer may be performed by, forexample, using a tin sulfate bath, at a plating temperature of 30° C. orlower, with a current density of 5 A/dm². The conditions are not limitedthereto and can be appropriately set up.

In the production of the metallic material for a connecting part of thefirst embodiment, when an underlying copper plating is provided, theratio (Sn thickness/Cu thickness) of the thickness of the surface tinplating or tin alloy plating layer (Sn thickness) to the thickness ofthe underlying copper plating layer (Cu thickness) is preferably lessthan 2, and more preferably equal to or greater than 1.0 and less than2.0.

Further, in the production of the metallic material for a connectingpart of the second embodiment, when an underlying copper plating isprovided, the ratio

(Sn thickness/Cu thickness) of the thickness of the surface layer tinplating or tin alloy plating layer (Sn thickness) to the thickness ofthe underlying copper plating layer (Cu thickness) is preferably 2 orgreater, and more preferably 2.0 to 3.0.

The metallic material for a connecting part of the present invention issubjected to a heat treatment in the longitudinal direction of therectangular wire material having a tin alloy plating layer formed at theoutermost layer by the plating described above. The heat treatment isnot particularly limited as long as it is a method capable of uniformlyheating the rectangular wire material, such as a reflow treatment. Whenthe metallic material is subjected to a treatment involving reflow, thetime for the heat treatment of the rectangular wire material can beshortened, and thus such an embodiment is preferable.

The metallic material for a connecting part of the present invention canbe processed in a usual manner, into various electrical/electronicconnectors, including, for example, fitting-type connectors and contactsfor automobiles.

In the metallic material for a connecting part of the first embodiment,the copper-tin alloy layer at the outermost surface also contains atleast one selected from the group consisting of zinc, indium, antimony,gallium, lead, bismuth, cadmium, magnesium, silver, gold, and aluminum,in a total amount of 0.01% or more and 1% or less, in terms of massratio with respect to the content of tin, and therefore, the metallicmaterial can be obtained as a metallic material for a connecting partwhich material is favorable in both the surface properties after theheat treatment and the solderability in the subsequent processes.

Furthermore, in the metallic material for a connecting part of thesecond embodiment, the alloy layer at the outermost surface containingcopper and tin contains an element selected from at least one groupamong the following two groups of (A) and (B), in a total amount of0.01% by mass or more and 2% by mass or less, and therefore, themetallic material can be obtained as a metallic material for aconnecting part which material is favorable in the surface propertiesafter the heat treatment and hardly generates whiskers.

(A) at least one element selected from the group consisting of Ga, In,Pb, Bi, Cd, Mg, Zn, Ag, and Au is contained, in an amount of 0.01% bymass or more and 1% by mass or less for individual element.

(B) at least one element selected from the group consisting of Al and Cuis contained, in an amount of 0.01 to 0.5% by mass for individualelement.

Examples

The present invention will be described in more detail based on examplesgiven below, but the invention is not meant to be limited by these.

In the following Examples (Invention Examples) and Comparative Examples,the conditions were as follows.

Base material: A rectangular wire of Corson alloy, in which the shape ofthe cross-section obtained by taking the longitudinal direction of therectangular wire as a perpendicular line is a square which measured 0.64mm on each side (manufactured by Furukawa Electric Co., Ltd., EFTEC-97:hereinafter, the same), was used. Hereinafter, one side of therectangular wire may be described with the term “width”. In regard tothe surface roughness, two types of base materials, one with Ra=2.0 μm(indicated as “Ra=large” in the tables) and one with Ra=0.05 μm(indicated as “Ra=small” in the tables), were used.

Plating: Copper plating was carried out using a sulfuric acid bath,nickel plating was carried out using a sulfamic acid bath, and tin alloyplating was carried out using a sulfuric acid bath. Here, the platingwas carried out by electroplating.

Tin alloy plating and elements added thereto: A liquid havingappropriate amounts of Zn ions, In ions, Cu ions, and Al ionsincorporated therein was prepared.

Measurement of concentration of additive element in tin plating: Platingwas carried out on a stainless steel, and only the plating coating wasdissolved in an acid, and the concentration was determined through ananalysis using an ICP emission analyzer.

Heat treatment: The metallic material was subjected to a reflowtreatment by heating on a hot plate.

Example 1

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to tin alloy plating to a thickness of 0.5 μm. Thereafter, thematerial was subjected to a reflow treatment at 350° C. for 10 seconds,and thus a rectangular wire material as shown in the partially enlargedschematic cross-sectional view of FIG. 1 was obtained. In FIG. 1, a partnear the center point of one side of the rectangular wire material isshown in an enlarged view (the same in the following figures). In FIG.1, the reference numeral 1 denotes a base material, and the referencenumeral 2 denotes a copper-tin alloy layer.

Comparative Example 1

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to tin alloy plating to a thickness of 0.5 μm. The amount ofthe additional elements in the tin alloy plating was selected such thatthe amount does not fall in the range of Example 1. Thereafter, thematerial was subjected to a reflow treatment at 350° C. for 10 seconds,and thus the rectangular wire material as shown in the partiallyenlarged schematic cross-sectional view of FIG. 1 was obtained.

Example 2

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to copper plating to a thickness of 0.3 μm, and then wassubjected to tin alloy plating to a thickness of 0.5 μm. Thereafter, thematerial was subjected to a reflow treatment at 500° C. for 5 seconds,and thus a rectangular wire material as shown in the partially enlargedschematic cross-sectional view of FIG. 2 was obtained. In FIG. 2, thereference numeral 1 denotes a base material, and the reference numeral 2denotes a copper-tin alloy layer. The copper plating layer hadcompletely reacted with the tin alloy plating of the outermost layer, bythe reflow treatment, and converted to a copper-tin alloy layer 2.

Comparative Example 2

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to copper plating to a thickness of 0.3 μm, and then wassubjected to tin alloy plating to a thickness of 0.5 μm. The amount ofthe additional elements in the tin alloy plating was selected such thatthe amount does not fall in the range of Example 2. Thereafter, thematerial was subjected to a reflow treatment at 350° C. for 10 seconds,and thus a rectangular wire material as shown in the partially enlargedschematic cross-sectional view of FIG. 2 was obtained. The copperplating layer had completely reacted with the tin alloy plating of theoutermost layer, by the reflow treatment, and converted to a copper-tinalloy layer 2.

Example 3

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to nickel plating to a thickness of 0.4 μm, subsequentlysubjected to copper plating to a thickness of 0.3 μm, and then subjectedto tin alloy plating to a thickness of 0.5 μm. Thereafter, the materialwas subjected to a reflow treatment at 500° C. for 5 seconds, and thus arectangular wire material as shown in the partially enlarged schematiccross-sectional view of FIG. 3 was obtained. In FIG. 3, the referencenumeral 1 denotes a base material, the reference numeral 2 denotes acopper-tin alloy layer, and the reference numeral 3 denotes a nickellayer. The copper plating layer had completely reacted with the tinalloy plating of the outermost layer, by the reflow treatment, andconverted to a copper-tin alloy layer 2.

Comparative Example 3

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to nickel plating to a thickness of 0.4 μm, subsequentlysubjected to copper plating to a thickness of 0.3 μm, and then subjectedto tin alloy plating to a thickness of 0.5 μm. The amount of theadditional elements in the tin alloy plating was selected such that theamount does not fall in the range of Example 3. Thereafter, the materialwas subjected to a reflow treatment at 350° C. for 10 seconds, and thusa rectangular wire material as shown in the partially enlarged schematiccross-sectional view of FIG. 3 was obtained. The copper plating layerhad completely reacted with the tin alloy plating of the outermostlayer, by the reflow treatment, and converted to a copper-tin alloylayer 2.

Test Example 1

The rectangular wire materials of Examples 1 to 3 and ComparativeExamples 1 to 3 were subjected to evaluation tests on contactresistance, solder wettability, and surface gloss. The results arerespectively presented in Tables 1-1 to 1-2 for Example 1 andComparative Example 1, in Tables 2-1 to 2-2 for Example 2 andComparative Example 2, and in Tables 3-1 to 3-2 for Example 3 andComparative Example 3.

(Contact Resistance)

The contact resistance was measured according to a four-terminal method.An Ag probe was used for a contact, and the measurement was made under aload of 1 N.

A contact resistance of 2 mΩ or less was designated to as good ∘∘, acontact resistance of 5 mΩ or less was designated to as acceptable(passed the test) ∘, and a higher contact resistance was designated toas unacceptable ×.

(Solder Wettability)

The solder wettability was measured according to a meniscograph method.

Solder Checker SAT-5100, manufactured by Rhesca Corp., was used for theapparatus.

A flux composed of 25% of rosin and the remainder of isopropyl alcoholwas applied on the surface of a rectangular wire, and then therectangular wire was immersed in a Sn-3.0Ag-0.5Cu lead-free solder bathmaintained at 260° C. The rectangular wire was maintained in the bathfor 3 seconds and then was pulled out.

The determination criteria were as follows: good ∘∘ when 95% or more ofthe immersed area was wet; acceptable ∘ when 90% or more of the immersedarea was wet; and unacceptable × when the wet area was less than that.

(Surface Gloss)

The surface gloss was examined by visual inspection. A rectangular wirehaving uniform gloss without any unevenness was rated as ∘∘; arectangular wire having slight dullness but having a gloss sufficient asa product, without any unevenness, was rated as ∘; and a rectangularwire having insufficient gloss or having unevenness was rated as ×.

TABLE 1-1 Zn in Cu in Gloss plating plating Underlying Contact Ra = Ra =No. (mass %) (mass %) plating resistance Solderability large smallRemarks 101 0 0.1 Not formed ∘ ∘ ∘ ∘∘ Example 102 0 0.01 Not formed ∘ ∘∘ ∘∘ according to 103 0.1 0 Not formed ∘ ∘ ∘ ∘∘ this invention 104 0.010 Not formed ∘ ∘ ∘ ∘∘ 105 1 0 Not formed ∘ ∘ ∘ ∘∘ 106 0.1 0.1 Not formed∘ ∘ ∘ ∘∘ 107 0.01 0.01 Not formed ∘ ∘ ∘ ∘∘ 111 0 1 Not formed ∘ x ∘ ∘∘Comparative 112 0 0.001 Not formed ∘ ∘ x x Example 113 0.001 0 Notformed ∘ ∘ x x 114 1 1 Not formed x ∘ ∘ ∘∘ 115 0.001 0.001 Not formed ∘∘ x x 116 0 0 Not formed ∘ ∘ x x

TABLE 1-2 In in Cu in Gloss plating plating Underlying Contact Ra = Ra =No. (mass %) (mass %) plating resistance Solderability large smallRemarks 103I 0.1 0 Not formed ∘ ∘∘ ∘ ∘∘ Example 104I 0.01 0 Not formed ∘∘ ∘ ∘∘ according to this 105I 1 0 Not formed ∘ ∘∘ ∘ ∘∘ invention 106I0.1 0.1 Not formed ∘ ∘∘ ∘ ∘∘ 107I 0.01 0.01 Not formed ∘ ∘ ∘ ∘∘ 113I0.001 0 Not formed ∘ ∘ x x Comparative 114I 1 1 Not formed x ∘∘ ∘ ∘∘Example 115I 0.001 0.001 Not formed ∘ ∘ x x

As shown in Tables 1-1 and 1-2, the samples of No. 101 to 107 and No.103I to 107I of Example 1 all satisfied the criteria for all of theitems of the contact resistance, the solderability, and the surfacegloss. Thus, the samples were suitable as a metallic material for aconnecting part such as a connector. On the contrary, the samples of No.111 to 116 and No. 113I to 115I of Comparative Example 1 wereunacceptable in at least one item among the contact resistance, thesolderability, and the surface gloss.

TABLE 2-1 Zn in Cu in Gloss plating plating Underlying Contact Ra = Ra =No. (mass %) (mass %) plating Resistance Solderability large smallRemarks 201 0 0.1 0.3 μm Cu ∘ ∘ ∘∘ ∘∘ Example 202 0 0.01 0.3 μm Cu ∘ ∘∘∘ ∘∘ according to 203 0.1 0 0.3 μm Cu ∘ ∘ ∘∘ ∘∘ this 204 0.01 0 0.3 μmCu ∘ ∘ ∘∘ ∘∘ invention 205 1 0 0.3 μm Cu ∘ ∘ ∘∘ ∘∘ 206 0.1 0.1 0.3 μm Cu∘ ∘ ∘∘ ∘∘ 207 0.01 0.01 0.3 μm Cu ∘ ∘ ∘∘ ∘∘ 211 0 1 0.3 μm Cu ∘ x ∘∘ ∘∘Comparative 212 0 0.001 0.3 μm Cu ∘ ∘ x ∘ example 213 0.001 0 0.3 μm Cu∘ ∘ x ∘ 214 1 1 0.3 μm Cu x ∘ ∘∘ ∘∘ 215 0.001 0.001 0.3 μm Cu ∘ ∘ x ∘216 0 0 0.3 μm Cu ∘ ∘ x ∘

TABLE 2-2 Gloss In in plating Cu in plating Underlying Contact Ra = Ra =No. (mass %) (mass %) plating resistance Solderability large smallRemarks 203I 0.1 0 0.3 μm Cu ∘ ∘∘ ∘∘ ∘∘ Example 204I 0.01 0 0.3 μm Cu ∘∘ ∘∘ ∘∘ according to 205I 1 0 0.3 μm Cu ∘ ∘∘ ∘∘ ∘∘ this 206I 0.1 0.1 0.3μm Cu ∘ ∘∘ ∘∘ ∘∘ invention 207I 0.01 0.01 0.3 μm Cu ∘ ∘ ∘∘ ∘∘ 213I 0.0010 0.3 μm Cu ∘ ∘ x ∘ Comparative 214I 1 1 0.3 μm Cu x ∘∘ ∘∘ ∘∘ example215I 0.001 0.001 0.3 μm Cu ∘ ∘ x ∘

As shown in Tables 2-1 and 2-2, the samples of Nos. 201 to 207 and Nos.203I to 207I of Example 2 all satisfied the criteria for all of theitems of the contact resistance, the solderability, and the surfacegloss. Thus, the samples were suitable as a metallic material for aconnecting part such as a connector. On the contrary, the samples ofNos. 211 to 216 and Nos. 213I to 215I of Comparative Example 2 wereunacceptable in at least one item among the contact resistance, thesolderability, and the surface gloss.

TABLE 3-1 Underlying plating Zn in Cu in Base Gloss plating platingmaterial Outermost Contact Ra = Ra = No. (mass %) (mass %) side layerside resistance Solderability large small Remarks 301 0 0.1 0.4 μm Ni0.3 μm Cu ∘ ∘ ∘∘ ∘∘ Example 302 0 0.01 0.4 μm Ni 0.3 μm Cu ∘ ∘ ∘∘ ∘∘according to 303 0.1 0 0.4 μm Ni 0.3 μm Cu ∘ ∘ ∘∘ ∘∘ this invention 3040.01 0 0.4 μm Ni 0.3 μm Cu ∘ ∘ ∘∘ ∘∘ 305 1 0 0.4 μm Ni 0.3 μm Cu ∘ ∘ ∘∘∘∘ 306 0.1 0.1 0.4 μm Ni 0.3 μm Cu ∘ ∘ ∘∘ ∘∘ 307 0.01 0.01 0.4 μm Ni 0.3μm Cu ∘ ∘ ∘∘ ∘∘ 311 0 1 0.4 μm Ni 0.3 μm Cu ∘ x ∘∘ ∘∘ Comparative 312 00.001 0.4 μm Ni 0.3 μm Cu ∘ ∘ x ∘ Example 313 0.001 0 0.4 μm Ni 0.3 μmCu ∘ ∘ x ∘ 314 1 1 0.4 μm Ni 0.3 μm Cu x ∘ ∘∘ ∘∘ 315 0.001 0.001 0.4 μmNi 0.3 μm Cu ∘ ∘ x ∘ 316 0 0 0.4 μm Ni 0.3 μm Cu ∘ ∘ x ∘

TABLE 3-2 Underlying plating In in Cu in Base Gloss plating platingmaterial Outermost Contact Ra = Ra = No. (mass %) (mass %) side layerside resistance Solderability large small Remarks 303I 0.1 0 0.4 μm Ni0.3 μm Cu ∘ ∘∘ ∘∘ ∘∘ Example 304I 0.01 0 0.4 μm Ni 0.3 μm Cu ∘ ∘ ∘∘ ∘∘according to 305I 1 0 0.4 μm Ni 0.3 μm Cu ∘ ∘∘ ∘∘ ∘∘ this 306I 0.1 0.10.4 μm Ni 0.3 μm Cu ∘ ∘∘ ∘∘ ∘∘ invention 307I 0.01 0.01 0.4 μm Ni 0.3 μmCu ∘ ∘ ∘∘ ∘∘ 313I 0.001 0 0.4 μm Ni 0.3 μm Cu ∘ ∘ x ∘ Comparative 314I 11 0.4 μm Ni 0.3 μm Cu x ∘∘ ∘∘ ∘ example 315I 0.001 0.001 0.4 μm Ni 0.3μm Cu ∘ ∘ x ∘

As shown in Tables 3-1 and 3-2, the samples of Nos. 301 to 307 and Nos.303I to 307I of Example 2 all satisfied the criteria for all the itemsof the contact resistance, the solderability, and the surface gloss.Thus, the samples were suitable as a metallic material for a connectingpart such as a connector. On the contrary, the samples of Nos. 311 to316 and Nos. 313I to 315I of Comparative Example 3 were unacceptable inat least one item among the contact resistance, the solderability, andthe surface gloss.

Example 4

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to tin alloy plating to a thickness of 0.9 μm. Thereafter, thematerial was subjected to a reflow treatment at 350° C. for 10 seconds,and thus a rectangular wire material as shown in the partially enlargedschematic cross-sectional view of FIG. 4 was obtained. In FIG. 4, a partnear the center point of one side of the rectangular wire material isshown in an enlarged view (the same in the following figures). In FIG.4, the reference numeral 11 denotes a base material, the referencenumeral 12 denotes a tin alloy plating layer, and the reference numeral13 denotes a copper-tin alloy layer.

Comparative Example 4

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to tin alloy plating to a thickness of 0.9 μm. The amount ofthe additional elements in the tin alloy plating was selected such thatthe amount does not fall in the range of Example 4. Thereafter, thematerial was subjected to a reflow treatment at 350° C. for 10 seconds,and thus a rectangular wire material as shown in the partially enlargedschematic cross-sectional view of FIG. 4 was obtained.

Example 5

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to copper plating to a thickness of 0.3 μm, and then wassubjected to tin alloy plating to a thickness of 0.9 μm. Thereafter, thematerial was subjected to a reflow treatment at 500° C. for 5 seconds,and thus a rectangular wire material as shown in the partially enlargedschematic cross-sectional view of FIG. 5 was obtained. In FIG. 5, thereference numeral 11 denotes a base material, the reference numeral 12denotes a tin alloy plating layer, and the reference numeral 13 denotesa copper-tin alloy layer. The copper plating layer had completelyreacted with the tin alloy plating of the outermost layer, by the reflowtreatment, and converted to a copper-tin alloy layer 13.

Comparative Example 5

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to copper plating to a thickness of 0.3 μm, and then wassubjected to tin alloy plating to a thickness of 0.9 μm. The amount ofthe additional elements in the tin alloy plating was selected such thatthe amount does not fall in the range of Example 5. Thereafter, thematerial was subjected to a reflow treatment at 350° C. for 10 seconds,and thus a rectangular wire material as shown in the partially enlargedschematic cross-sectional view of FIG. 5 was obtained. The copperplating layer had completely reacted with the tin alloy plating of theoutermost layer, by the reflow treatment, and converted to a copper-tinalloy layer 13.

Example 6

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to nickel plating to a thickness of 0.4 μm, and then subjectedto tin alloy plating to a thickness of 0.9 μm. Thereafter, the materialwas subjected to a reflow treatment at 350° C. for 10 seconds, and thusa rectangular wire material as shown in the partially enlarged schematiccross-sectional view of FIG. 6 was obtained. In FIG. 6, the referencenumeral 11 denotes a base material, the reference numeral 12 denotes atin alloy plating layer, and the reference numeral 14 denotes a nickellayer.

Comparative Example 6

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to nickel plating to a thickness of 0.4 μm, and then subjectedto tin alloy plating to a thickness of 0.9 μm. The amount of theadditional elements in the tin alloy plating was selected such that theamount does not fall in the range of Example 6. Thereafter, the materialwas subjected to a reflow treatment at 350° C. for 10 seconds, and thusa rectangular wire material as shown in the partially enlarged schematiccross-sectional view of FIG. 6 was obtained.

Example 7

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to nickel plating to a thickness of 0.4 μm, subsequentlysubjected to copper plating to a thickness of 0.3 μm, and then subjectedto tin alloy plating to a thickness of 0.9 μm. Thereafter, the materialwas subjected to a reflow treatment at 500° C. for 5 seconds, and thus arectangular wire material as shown in the partially enlarged schematiccross-sectional view of FIG. 7 was obtained. In FIG. 7, the referencenumeral 11 denotes a base material, the reference numeral 12 denotes atin alloy plating layer, the reference numeral 13 denotes a copper-tinalloy layer, and the reference numeral 14 denotes a nickel layer. Thecopper plating layer had completely reacted with the tin alloy platingof the outermost layer, by the reflow treatment, and converted to acopper-tin alloy layer 13.

Comparative Example 7

A rectangular wire of Corson alloy having a width of 0.64 mm wassubjected to nickel plating to a thickness of 0.4 μm, subsequentlysubjected to copper plating to a thickness of 0.3 μm, and then subjectedto tin alloy plating to a thickness of 0.9 μm. The amount of theadditional elements in the tin alloy plating was selected such that theamount does not fall in the range of Example. Thereafter, the materialwas subjected to a reflow treatment at 350° C. for 10 seconds, and thusa rectangular wire material as shown in the partially enlarged schematiccross-sectional view of FIG. 7 was obtained. The copper plating layerhad completely reacted with the tin alloy plating of the outermostlayer, by the reflow treatment, and converted to a copper-tin alloylayer 13.

Test Example 2

The rectangular wire materials of Examples 4 to 7 and ComparativeExamples 4 to 7 were subjected to evaluation tests on surface gloss,whisker preventing property, and contact resistance. The results arerespectively presented in Tables 4-1 to 4-4 for Example 4 andComparative Example 4, in Tables 5-1 to 5-4 for Example 5 andComparative Example 5, in Tables 6-1 to 6-4 for Example 6 andComparative Example 6, and in Tables 7-1 to 7-4 for Example 7 andComparative Example 7.

(Surface Gloss)

The surface gloss was examined by visual inspection. A rectangular wirehaving uniform gloss without any unevenness was rated as ∘∘; arectangular wire having slight dullness but having a gloss sufficient asa product, without any unevenness, was rated as ∘; and a rectangularwire having insufficient gloss or having unevenness was rated as ×.

(Whisker Preventing Property)

A rectangular wire was left to stand for three months while an externalstress was exerted to the rectangular wire by an indenter, and thepresence or absence of the generation of whiskers was investigated. Arectangular wire which did not generate whiskers or which generatedwhiskers having a length of 50 μm or less, was rated as ∘; and arectangular wire which generated whiskers having a length of greaterthan 50 μm was rated as ×.

(Contact Resistance)

Common to all samples: A sample was exposed to an atmosphere at 120° C.for 120 hours, and then the contact resistance was measured. Themeasurement was made according to a four-terminal method, under a loadof 1 N, using an Ag probe as a contact.

A contact resistance of 2 mΩ or less was designated as good ∘∘; acontact resistance of 5 mΩ or less was designated as acceptable ∘; and acontact resistance higher than that was designated as unacceptable ×.

Example 6, Comparative Example 6, Example 7, and Comparative Example 7:With a method for measurement conducted in the same manner as the methodafter heating at 120° C. for 120 hours, the contact resistance obtainedafter exposure to an atmosphere at 160° C. for 120 hours was alsomeasured.

TABLE 4-1 Cu in Zn in outermost outermost Gloss Contact Whisker layerlayer Underlying Ra = Ra = resistance preventing No. (mass %) (mass %)plating large small after heating property Remarks 401 0.1 0 Not formed∘ ∘∘ ∘ ∘ Example 402 0.01 0 Not formed ∘ ∘∘ ∘ ∘ according to 403 0 0.1Not formed ∘ ∘∘ ∘ ∘ this invention 404 0 0.01 Not formed ∘ ∘∘ ∘ ∘ 4050.1 0.1 Not formed ∘ ∘∘ ∘ ∘ 406 0.01 0.01 Not formed ∘ ∘∘ ∘ ∘ 411 1 0Not formed ∘ ∘∘ ∘ x Comparative 412 0.001 0 Not formed x x ∘ ∘ example413 0 1 Not formed ∘ ∘∘ x ∘ 414 0 0.001 Not formed x x ∘ ∘ 415 1 1 Notformed ∘ ∘∘ x ∘ 416 0.001 0.001 Not formed x x ∘ ∘ 417 0 0 Not formed xx ∘ ∘

TABLE 4-2 Cu in In in Contact outermost outermost Gloss resistanceWhisker layer layer Underlying Ra = Ra = after preventing No. (mass %)(mass %) plating large small heating property Remarks 403I 0 0.1 Notformed ∘ ∘∘ ∘∘ ∘ Example 404I 0 0.01 Not formed ∘ ∘∘ ∘ ∘ according to405I 0.1 0.1 Not formed ∘ ∘∘ ∘∘ ∘ this 406I 0.01 0.01 Not formed ∘ ∘∘ ∘∘ invention 413I 0 1 Not formed ∘ ∘∘ ∘ x Comparative 414I 0 0.001 Notformed x x ∘ ∘ example 415I 1 1 Not formed ∘ ∘∘ x ∘ 416I 0.001 0.001 Notformed x x ∘ ∘

TABLE 4-3 Al in Zn in Contact outermost outermost Gloss resistanceWhisker layer layer Underlying Ra = Ra = after preventing No. (mass %)(mass %) plating large small heating property Remarks 401AZ 0.1 0 Notformed ∘ ∘∘ ∘ ∘ Example 402AZ 0.01 0 Not formed ∘ ∘∘ ∘ ∘ according to405AZ 0.1 0.1 Not formed ∘ ∘∘ ∘ ∘ this 406AZ 0.01 0.01 Not formed ∘ ∘∘ ∘∘ invention 411AZ 1 0 Not formed ∘ ∘∘ x ∘ Comparative 412AZ 0.001 0 Notformed x x ∘ ∘ example 415AZ 1 1 Not formed ∘ ∘∘ x ∘ 416AZ 0.001 0.001Not formed x x ∘ ∘

TABLE 4-4 Al in In in outermost outermost Gloss Contact Whisker layerlayer Underlying Ra = Ra = resistance preventing No. (mass %) (mass %)plating large small after heating property Remarks 405AI 0.1 0.1 Notformed ∘∘ ∘∘ ∘ ∘ Example according 406AI 0.01 0.01 Not formed ∘ ∘∘ ∘ ∘to this invention 415AI 1 1 Not formed ∘ ∘∘ x ∘ Comparative 416AI 0.0010.001 Not formed x x ∘ ∘ example

As shown in Tables 4-1 to 4-4, the samples of Nos. 401 to 406, Nos. 403Ito 406I, Nos. 401AZ to 402AZ, Nos. 405AZ to 406AZ, and Nos. 405AI to406AI of Example 4 all satisfied the criteria for all of the items ofthe surface gloss, the whisker preventing property, and the contactresistance. Thus, the samples were suitable as a metallic material for aconnecting part such as a connector. On the contrary, the samples ofNos. 411 to 417, Nos. 413I to 416I, Nos. 411AZ to 412AZ, Nos. 415AZ to416AZ, and Nos. 415AI to 416AI of Comparative Example 4 wereunacceptable in at least one of the surface gloss, the whiskerpreventing property, and the contact resistance.

TABLE 5-1 Cu in Zn in Contact outermost outermost Gloss resistanceWhisker layer layer Underlying Ra = Ra = after preventing No. (mass %)(mass %) plating large small heating property Remarks 501 0.1 0 0.3 μmCu ∘∘ ∘∘ ∘ ∘ Exmple 502 0.01 0 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ according to 503 00.1 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ this 504 0 0.01 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ invention505 0.1 0.1 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ 506 0.01 0.01 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ 511 10 0.3 μm Cu ∘∘ ∘∘ ∘ x Comparative 512 0.001 0 0.3 μm Cu x ∘ ∘ ∘ example513 0 1 0.3 μm Cu ∘∘ ∘∘ x ∘ 514 0 0.001 0.3 μm Cu x ∘ ∘ ∘ 515 1 1 0.3 μmCu ∘∘ ∘∘ x ∘ 516 0.001 0.001 0.3 μm Cu x ∘ ∘ ∘ 517 0 0 0.3 μm Cu x ∘ ∘ ∘

TABLE 5-2 Cu in In in Contact outermost outermost Gloss resistanceWhisker layer layer Underlying Ra = Ra = after preventing No. (mass %)(mass %) plating large small heating property Remarks 503I 0 0.1 0.3 μmCu ∘∘ ∘∘ ∘∘ ∘ Example 504I 0 0.01 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ according to 505I0.1 0.1 0.3 μm Cu ∘∘ ∘∘ ∘∘ ∘ this 506I 0.01 0.01 0.3 μm Cu ∘∘ ∘∘ ∘ ∘invention 513I 0 1 0.3 μm Cu ∘∘ ∘∘ ∘ x Comparative 514I 0 0.001 0.3 μmCu x ∘ ∘ ∘ example 515I 1 1 0.3 μm Cu ∘∘ ∘∘ x ∘ 516I 0.001 0.001 0.3 μmCu x ∘ ∘ ∘

TABLE 5-3 Al in Zn in Contact outermost outermost Gloss resistanceWhisker layer layer Underlying Ra = Ra = after preventing No. (mass %)(mass %) plating large small heating property Remarks 501AZ 0.1 0 0.3 μmCu ∘∘ ∘∘ ∘ ∘ Example 502AZ 0.01 0 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ according to 505AZ0.1 0.1 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ this 506AZ 0.01 0.01 0.3 μm Cu ∘∘ ∘∘ ∘ ∘invention 511AZ 1 0 0.3 μm Cu ∘∘ ∘∘ x ∘ Comparative 512AZ 0.001 0 0.3 μmCu x ∘ ∘ ∘ example 515AZ 1 1 0.3 μm Cu ∘∘ ∘∘ x ∘ 516AZ 0.001 0.001 0.3μm Cu x ∘ ∘ ∘

TABLE 5-4 Al in In in outermost outermost Gloss Contact Whisker layerlayer Underlying Ra = Ra = resistance preventing No. (mass %) (mass %)plating large small after heating property Remarks 505AI 0.1 0.1 0.3 μmCu ∘∘ ∘∘ ∘∘ ∘ Example according 506AI 0.01 0.01 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ tothis invention 515AI 1 1 0.3 μm Cu ∘∘ ∘∘ x ∘ Comparative 516AI 0.0010.001 0.3 μm Cu x ∘ ∘ ∘ example

As shown in Tables 5-1 to 5-4, the samples of Nos. 501 to 506, Nos. 503Ito 506I, Nos. 501AZ to 502AZ, Nos. 505AZ to 506AZ, and Nos. 505AI to506AI of Example 5 all satisfied the criteria for all of the items ofthe surface gloss, the whisker preventing property, and the contactresistance. Thus, the samples were suitable as a metallic material for aconnecting part such as a connector. On the contrary, the samples ofNos. 511 to 517, Nos. 513I to 516I, Nos. 511AZ to 512AZ, Nos. 515AZ to516AZ, and Nos. 515AI to 516AI of Comparative Example 5 wereunacceptable in at least one of the surface gloss, the whiskerpreventing property, and the contact resistance.

TABLE 6-1 Cu in Zn in Contact outermost outermost Gloss resistance afterWhisker layer layer Underlying Ra = Ra = heating preventing No. (mass %)(mass %) plating large small 120° C. 160° C. property Remarks 601 0.1 00.4 μm Ni ∘∘ ∘∘ ∘ ∘ ∘ Example 602 0.01 0 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ ∘ accordingto 603 0 0.1 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ ∘ this invention 604 0 0.01 0.4 μm Ni∘∘ ∘∘ ∘ ∘ ∘ 605 0.1 0.1 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ ∘ 606 0.01 0.01 0.4 μm Ni ∘∘∘∘ ∘ ∘ ∘ 611 1 0 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ x Comparative 612 0.001 0 0.4 μm Nix ∘ ∘ ∘ ∘ example 613 0 1 0.4 μm Ni ∘∘ ∘∘ x x ∘ 614 0 0.001 0.4 μm Ni x∘ ∘ ∘ ∘ 615 1 1 0.4 μm Ni ∘∘ ∘∘ x x ∘ 616 0.001 0.001 0.4 μm Ni x ∘ ∘ ∘∘ 617 0 0 0.4 μm Ni x ∘ ∘ ∘ ∘

TABLE 6-2 Cu in In in Contact outermost outermost Gloss resistance afterWhisker layer layer Underlying Ra = Ra = heating preventing No. (mass %)(mass %) plating large small 120° C. 160° C. property Remarks 603I 0 0.10.4 μm Ni ∘∘ ∘∘ ∘∘ ∘ ∘ Example 604I 0 0.01 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ ∘according to 605I 0.1 0.1 0.4 μm Ni ∘∘ ∘∘ ∘∘ ∘ ∘ this 606I 0.01 0.01 0.4μm Ni ∘∘ ∘∘ ∘ ∘ ∘ invention 613I 0 1 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ x Comparative614I 0 0.001 0.4 μm Ni x ∘ ∘ ∘ ∘ example 615I 1 1 0.4 μm Ni ∘∘ ∘∘ x x ∘6161 0.001 0.001 0.4 μm Ni x ∘ ∘ ∘ ∘

TABLE 6-3 Al in Zn in Contact outermost outermost Gloss resistanceWhisker layer layer Underlying Ra = Ra = after heating preventing No.(mass %) (mass %) plating large small 120° C. 160° C. property Remarks601AZ 0.1 0 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ ∘ Example 602AZ 0.01 0 0.4 μm Ni ∘∘ ∘∘ ∘∘ ∘ according to 605AZ 0.1 0.1 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ ∘ this invention606AZ 0.01 0.01 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ ∘ 611AZ 1 0 0.4 μm Ni ∘∘ ∘∘ x x ∘Comparative 612AZ 0.001 0 0.4 μm Ni x ∘ ∘ ∘ ∘ example 615AZ 1 1 0.4 μmNi ∘∘ ∘∘ x x ∘ 616AZ 0.001 0.001 0.4 μm Ni x ∘ ∘ ∘ ∘

TABLE 6-4 Al in In in Contact outermost outermost Gloss resistance afterWhisker layer layer Underlying Ra = Ra = heating preventing No. (mass %)(mass %) plating large small 120° C. 160° C. property Remarks 605AI 0.10.1 0.4 μm Ni ∘∘ ∘∘ ∘∘ ∘ ∘ Example 606AI 0.01 0.01 0.4 μm Ni ∘∘ ∘∘ ∘ ∘ ∘according to this invention 615AI 1 1 0.4 μm Ni ∘∘ ∘∘ x x ∘ Comparative616AI 0.001 0.001 0.4 μm Ni x ∘ ∘ ∘ ∘ example

As shown in Tables 6-1 to 6-4, the samples of Nos. 601 to 606, Nos. 603Ito 606I, Nos. 601AZ to 602AZ, Nos. 605AZ to 606AZ, and Nos. 605AI to606AI of Example 6 all satisfied the criteria for all of the items ofthe surface gloss, the whisker preventing property, and the contactresistance. Thus, the samples were suitable as a metallic material for aconnecting part such as a connector. On the contrary, the samples ofNos. 611 to 617, Nos. 613I to 616I, Nos. 611AZ to 612AZ, Nos. 615AZ to616AZ, and Nos. 615AI to 616AI of Comparative Example 6 wereunacceptable in at least one of the surface gloss, the whiskerpreventing property, and the contact resistance.

TABLE 7-1 Underlying Cu in Zn in plating Contact outermost outermostBase Gloss resistance Whisker layer layer material Outermost Ra = Ra =after heating preventing No. (mass %) (mass %) side layer side largesmall 120° C. 160° C. property Remarks 701 0.1 0 0.4 μm Ni 0.3 μm Cu ∘∘∘∘ ∘ ∘ ∘ Example 702 0.01 0 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘ according to703 0 0.1 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘ this 704 0 0.01 0.4 μm Ni 0.3μm Cu ∘∘ ∘∘ ∘ ∘ ∘ invention 705 0.1 0.1 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘706 0.01 0.01 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘ 711 1 0 0.4 μm Ni 0.3 μmCu ∘∘ ∘∘ ∘ ∘ x Comparative 712 0.001 0 0.4 μm Ni 0.3 μm Cu x ∘ ∘ ∘ ∘example 713 0 1 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ x x ∘ 714 0 0.001 0.4 μm Ni0.3 μm Cu x ∘ ∘ ∘ ∘ 715 1 1 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ x x ∘ 716 0.0010.001 0.4 μm Ni 0.3 μm Cu x ∘ ∘ ∘ ∘ 717 0 0 0.4 μm Ni 0.3 μm Cu x ∘ ∘ ∘∘

TABLE 7-2 Underlying Cu in In in plating Contact outermost outermostBase Gloss resistance Whisker layer layer material Outermost Ra = Ra =after heating preventing No. (mass %) (mass %) side layer side largesmall 120° C. 160° C. property Remarks 703I 0 0.1 0.4 μm Ni 0.3 μm Cu ∘∘∘∘ ∘∘ ∘ ∘ Example 704I 0 0.01 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘ accordingto 705I 0.1 0.1 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘∘ ∘ ∘ this invention 706I0.01 0.01 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘ 713I 0 1 0.4 μm Ni 0.3 μm Cu∘∘ ∘∘ ∘ ∘ x Comparative 714I 0 0.001 0.4 μm Ni 0.3 μm Cu x ∘ ∘ ∘ ∘example 715I 1 1 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ x x ∘ 716I 0.001 0.001 0.4 μmNi 0.3 μm Cu x ∘ ∘ ∘ ∘

TABLE 7-3 Underlying Al in Zn in plating Contact outermost outermostBase Gloss resistance Whisker layer layer material Outermost Ra = Ra =after heating preventing No. (mass %) (mass %) side layer side largesmall 120° C. 160° C. property Remarks 701AZ 0.1 0 0.4 μm Ni 0.3 μm Cu∘∘ ∘∘ ∘ ∘ ∘ Example 702AZ 0.01 0 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘according to 705AZ 0.1 0.1 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘ this 706AZ0.01 0.01 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘ invention 711AZ 1 0 0.4 μm Ni0.3 μm Cu ∘∘ ∘∘ x x ∘ Comparative 712AZ 0.001 0 0.4 μm Ni 0.3 μm Cu x ∘∘ ∘ ∘ example 715AZ 1 1 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ x x ∘ 716AZ 0.0010.001 0.4 μm Ni 0.3 μm Cu x ∘ ∘ ∘ ∘

TABLE 7-4 Underlying Al in In in plating Contact outermost outermostBase Gloss resistance Whisker layer layer material Outermost Ra = Ra =after heating preventing No. (mass %) (mass %) side layer side largesmall 120° C. 160° C. property Remarks 705AI 0.1 0.1 0.4 μm Ni 0.3 μm Cu∘∘ ∘∘ ∘∘ ∘ ∘ Example 706AI 0.01 0.01 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ ∘ ∘ ∘according to this invention 715AI 1 1 0.4 μm Ni 0.3 μm Cu ∘∘ ∘∘ x x ∘Comparative 716AI 0.001 0.001 0.4 μm Ni 0.3 μm Cu x ∘ ∘ ∘ ∘ example

As shown in Tables 7-1 to 7-4, the samples of Nos. 701 to 706, Nos. 703Ito 706I, Nos. 701AZ to 702AZ, Nos. 705AZ to 706AZ, and Nos. 705AI to706AI of Example 7 all satisfied the criteria for all of the items ofthe surface gloss, the whisker preventing property, and the contactresistance. Thus, the samples were suitable as a metallic material for aconnecting part such as connectors. On the contrary, the samples of Nos.711 to 717, Nos. 713I to 716I, Nos. 711AZ to 712AZ, Nos. 715AZ to 716AZ,and Nos. 715AI to 716AI of Comparative Example 7 were unacceptable in atleast one of the surface gloss, the whisker preventing property, and thecontact resistance.

Having described our invention as related to the present embodiments, itis our intention that the invention not be limited by any of the detailsof the description, unless otherwise specified, but rather be construedbroadly within its spirit and scope as set out in the accompanyingclaims.

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2008-092053 filed in Japan on Mar. 31,2008, and Patent Application No. 2008-092054 filed in Japan on Mar. 31,2008, each of which is entirely herein incorporated by reference.

1. A metallic material for a connecting part, having a rectangular wirematerial of copper or a copper alloy as a base material, and formed atan outermost surface thereof, a copper-tin alloy layer substantiallycomposed of copper and tin, wherein the copper-tin alloy layer of theoutermost surface further contains at least one selected from the groupconsisting of zinc, indium, antimony, gallium, lead, bismuth, cadmium,magnesium, silver, gold and aluminum, in a total amount of 0.01% or moreand 1% or less in terms of mass ratio with respect to the content of thetin.
 2. The metallic material for a connecting part according to claim1, wherein a layer of nickel, cobalt, iron, or an alloy thereof isformed on the base material. 15
 3. A metallic material for a connectingpart, having a rectangular wire material of copper or a copper alloy asa base material, and formed at an outermost surface thereof, an alloylayer containing tin as a main component, wherein the alloy layercontaining tin as a main component at the outermost surface contains anelement selected from at least one group among the following two groupsof (A) and (B), in a total amount of 0.01% by mass or more and 2% bymass or less: (A) at least one element selected from the groupconsisting of gallium, indium, lead, bismuth, cadmium, magnesium, zinc,sliver, and gold is contained, in an amount of 0.01% by mass or more and1% by mass or less for individual element, and (B) at least one elementselected from the group consisting of aluminum and copper is contained,in an amount of 0.01 to 0.5% by mass for individual element.
 4. Themetallic material for a connecting part according to claim 3, wherein alayer of nickel, cobalt, iron, or an alloy thereof is formed on the basematerial.
 5. A method for producing a metallic material for a connectingpart, the method including: providing a rectangular wire material ofcopper or a copper alloy as a base material, forming on this basematerial a tin alloy plating layer containing at least one selected fromthe group consisting of zinc, indium, antimony, gallium, lead, bismuth,cadmium, magnesium, silver, gold, copper and aluminum, in a total amountof 0.01% by mass or more and 1% by mass or less, to thereby obtain anintermediate material; subsequently subjecting the intermediate materialto a heat treatment, and thereby forming an alloy layer containingcopper and tin at the outermost surface.
 6. The method for producing ametallic material for a connecting part according to claim 5, whereinthe heat treatment is a reflow treatment.
 7. The method for producing ametallic material for a connecting part according to claim 5, whereinthe thickness of the tin alloy plating layer prior to the heat treatmentis 0.3 to 0.8 μm.
 8. The method for producing a metallic material for aconnecting part according to claim 7, wherein the heat treatment is areflow treatment.
 9. The method for producing a metallic material for aconnecting part according to claim 5, wherein a layer of nickel, cobalt,iron, or an alloy thereof, and a copper plating layer or a copper alloyplating layer are provided, in order from the side closer to the basematerial, between the base material and the tin alloy plating layer, andthereby the intermediate material is obtained.
 10. The method forproducing a metallic material for a connecting part according to claim9, wherein the heat treatment is a reflow treatment.
 11. The method forproducing a metallic material for a connecting part according to claim9, wherein the thickness of the tin alloy plating layer prior tosubjecting to the heat treatment is 0.3 to 0.8 μM, and the ratio (Snthickness/Cu thickness) of the thickness of the tin plating or tin alloyplating layer (Sn thickness) to the thickness of the copper platinglayer (Cu thickness) is less than
 2. 12. The method for producing ametallic material for a connecting part according to claim 11, whereinthe heat treatment is a reflow treatment.
 13. A method for producing ametallic material for a connecting part, the method including: providinga rectangular wire material of copper or a copper alloy as a basematerial, forming on this base material a tin alloy plating layercontaining an element selected from at least one group among thefollowing two groups (A) and (B), in a total amount of 0.01% by mass ormore and 2% by mass or less, to thereby obtain an intermediate material;and then subjecting the intermediate material to a heat treatment: (A)at least one element selected from the group consisting of gallium,indium, lead, bismuth, cadmium, magnesium, zinc, sliver, and gold iscontained, in an amount of 0.01% by mass or more and 1% by mass or lessfor individual element, and (B) at least one element selected from thegroup consisting of aluminum and copper is contained, in an amount of0.01 to 0.5% by mass for individual element.
 14. The method forproducing a metallic material for a connecting part according to claim13, wherein the heat treatment is a reflow treatment.
 15. The method forproducing a metallic material for a connecting part according to claim13, wherein the thickness of the tin alloy plating layer prior to theheat treatment is 0.8 to 1.2 μm.
 16. The method for producing a metallicmaterial for a connecting part according to claim 15, wherein the heattreatment is a reflow treatment.
 17. The method for producing a metallicmaterial for a connecting part according to claim 13, wherein a layer ofnickel, cobalt, iron or an alloy thereof, and a copper plating layer ora copper alloy plating layer are provided, in order from the side closerto the base material, between the base material and the tin alloyplating layer, and thereby the intermediate material is obtained. 18.The method for producing a metallic material for a connecting partaccording to claim 17, wherein the heat treatment is a reflow treatment.19. The method for producing a metallic material for a connecting partaccording to claim 17, wherein the thickness of the tin alloy platinglayer prior to subjecting to the heat treatment is 0.8 to 1.2 μm, andthe ratio (Sn thickness/Cu thickness) of the thickness of the tinplating or tin alloy plating layer (Sn thickness) to the thickness ofthe copper plating layer (Cu thickness) is 2 or more.
 20. The method forproducing a metallic material for a connecting part according to claim19, wherein the heat treatment is a reflow treatment.